Metal powders, such as those utilized in additive manufacturing processes, frequently need to be classified, degassed, and/or heat treated before they are able to be used in an industrial process. By way of example, powders for a cold spray process must be classified into particle size ranges, to ensure that the particles used are within acceptable tolerances. Further, it may be desirable in some examples to degas the powder particles in order to remove any contaminants adsorbed on the surface of the powder. The contaminants can be any other material, including water moisture or similar atmospheric contaminants adsorbed on the surfaces of the powder. It may also be desirable to heat treat the powder to achieve the correct powder structure, for example solution treating, annealing, homogenizing, etc.
Existing classification systems utilize sieves or use air or inert gas classification. Sieves are inefficient at removal of fine particles and typical gas classification systems, even those that utilize inert gas, require the powder to be exposed to the atmosphere before or after the classification process. Neither of these processes address the needs for heat treatment or degassing
Existing degassing processes use a vacuum to draw moisture or other contaminants off of powder surfaces. This process is long due to the low transport rate of these contaminants through the bed. In a fluidized bed transport is enabled by the flow of an inert gas through the bed.
Other existing heat treatment processes include static heat treatment of powder in a furnace or in some cases in a rotating tube furnace. In either case no classification is performed, and the powder is exposed to the atmosphere during transfer to secondary containers.